1991 Vol. 4, No. 1
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1991, 4(1): 1-9.
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Abstract:
According to the chemical analyses of both leaves from 63 species of plants and 25 species of timbers, the chemical characteristics of plants and different vegetation types in tropical forests and the contents of the major elements were studied with the applications of both principal component analysis and cluster analysis. From the view-point of chemistry, the regulations of structure, function and the space distribution of the tropical forests had been revealed. The percentage of element contents of both leaves and stems are as follows:C 45.13, SiO2 2.05, N1.68, K0.87, Ca0.47, Mg0.22, P0.08 and ash 5.87 are in leaves, C 48.44, N0.82, SiO2 0.59, K0.19, Ca 0.045, Mg 0.042, P0.013 and ash 2.104 are in stems. Their quantities in different forests in orders are semideciduous monsoon forest, evergreen monsoon forest, mountain rain forest and mossy forest. The types of phytochemistry of leaves were divided into five or six groups by both of the principal component analysis and cluster analysis. The conclusion of the research has an important academic value for the further study on the tropical forest ecosystem, providing basic background data.
According to the chemical analyses of both leaves from 63 species of plants and 25 species of timbers, the chemical characteristics of plants and different vegetation types in tropical forests and the contents of the major elements were studied with the applications of both principal component analysis and cluster analysis. From the view-point of chemistry, the regulations of structure, function and the space distribution of the tropical forests had been revealed. The percentage of element contents of both leaves and stems are as follows:C 45.13, SiO2 2.05, N1.68, K0.87, Ca0.47, Mg0.22, P0.08 and ash 5.87 are in leaves, C 48.44, N0.82, SiO2 0.59, K0.19, Ca 0.045, Mg 0.042, P0.013 and ash 2.104 are in stems. Their quantities in different forests in orders are semideciduous monsoon forest, evergreen monsoon forest, mountain rain forest and mossy forest. The types of phytochemistry of leaves were divided into five or six groups by both of the principal component analysis and cluster analysis. The conclusion of the research has an important academic value for the further study on the tropical forest ecosystem, providing basic background data.
1991, 4(1): 10-14.
Abstract:
The migration of the birds of prey has a close relation with the climate through our observation in Laotieshan, Dalian City, Dahiesh-andao, Changdao County, Shandong Province and Fushan, Qingdao from 1986 to 1987. The key reason that force the birds of prey to move to the warm south is that the seasonal change of the climate resulted in autumn. The birds of prey prefer to move in a northwest or south wind that is above 14km per hour. It is the very day or the following day after the pushing through of the cold front on the ground that this kind of atmospheric circulation will show itself on the weather map. The main feature of the weather prior to the going through of the cold front is the coming of south and southwest wind with the rise of temperature. After the cold front, it changes to west and northwest wind with the declination of air temperature and increase of atmospheric pressure and acceleration of wind speed. Big flocks of birds will get through under the weather of northwest wind, the wind force is 30~40 km per hour, so that we can forecast the migration of the birds of prey according to the weather changing patterns worked out in this research work.
The migration of the birds of prey has a close relation with the climate through our observation in Laotieshan, Dalian City, Dahiesh-andao, Changdao County, Shandong Province and Fushan, Qingdao from 1986 to 1987. The key reason that force the birds of prey to move to the warm south is that the seasonal change of the climate resulted in autumn. The birds of prey prefer to move in a northwest or south wind that is above 14km per hour. It is the very day or the following day after the pushing through of the cold front on the ground that this kind of atmospheric circulation will show itself on the weather map. The main feature of the weather prior to the going through of the cold front is the coming of south and southwest wind with the rise of temperature. After the cold front, it changes to west and northwest wind with the declination of air temperature and increase of atmospheric pressure and acceleration of wind speed. Big flocks of birds will get through under the weather of northwest wind, the wind force is 30~40 km per hour, so that we can forecast the migration of the birds of prey according to the weather changing patterns worked out in this research work.
1991, 4(1): 15-21.
Abstract:
Various experimental methods were used to test natural resistance to moulds of the timber of eleven bamboo species, and the timber of Mao bamboo (Phyllostachys edulis (Carr.) H. de Lahaie) of different ages and from different positions on the stem. Bamboos were from north Zhe-jiang, the People's Republic of China. The results from analysis of variance and multiple contrasts were as follows:(1) The sequence of natural resistance of the timber of eleven bamboo species to the moulds from high to low was Phyllostachys edulis f. luteosulcata (Wen) Chao et Renv., P. edulis (Carr.) H. de Lahaie, P. meyeri McClure, P. viridis (Young) McClure and P. nuda McClure, P. iridenscens C. Y. Yao et S. Y. Chen and P. nigra Munro var. henonis (Miff) Stapt ex Rendle, P. nidularia cv smoothsheath McClure, Pleioblastus amurus Keng f., Phyllostachys angusta McClure, Pseudosasa amabilis Keng f.; the first two were resistant bamboo timbers and the last four were sensitive timbers, there was significant difference between them; interactions of bamboo speciespretreatm-ents and bamboo speciestemperatures and humidities existed.(2) The resistance to the moulds of winter-felled Mao bamboo timber increased with the age of the bamboo, the timber of 9~12 years old Mao bamboo was significantly more resistant than that of 3~8 years old ones; the timber from the upper part of the Mao bamboo stem was significantly resistant than that from the middle and lower part of the same stem.
Various experimental methods were used to test natural resistance to moulds of the timber of eleven bamboo species, and the timber of Mao bamboo (Phyllostachys edulis (Carr.) H. de Lahaie) of different ages and from different positions on the stem. Bamboos were from north Zhe-jiang, the People's Republic of China. The results from analysis of variance and multiple contrasts were as follows:(1) The sequence of natural resistance of the timber of eleven bamboo species to the moulds from high to low was Phyllostachys edulis f. luteosulcata (Wen) Chao et Renv., P. edulis (Carr.) H. de Lahaie, P. meyeri McClure, P. viridis (Young) McClure and P. nuda McClure, P. iridenscens C. Y. Yao et S. Y. Chen and P. nigra Munro var. henonis (Miff) Stapt ex Rendle, P. nidularia cv smoothsheath McClure, Pleioblastus amurus Keng f., Phyllostachys angusta McClure, Pseudosasa amabilis Keng f.; the first two were resistant bamboo timbers and the last four were sensitive timbers, there was significant difference between them; interactions of bamboo speciespretreatm-ents and bamboo speciestemperatures and humidities existed.(2) The resistance to the moulds of winter-felled Mao bamboo timber increased with the age of the bamboo, the timber of 9~12 years old Mao bamboo was significantly more resistant than that of 3~8 years old ones; the timber from the upper part of the Mao bamboo stem was significantly resistant than that from the middle and lower part of the same stem.
1991, 4(1): 22-29.
Abstract:
The paper deals with the biomass of average 20-aged Bruguiera gymnorrhiza stand. The vertical stratification method was adopted to measure the above ground biomass of different size-class trees in the stand. The tree mean growing area method was adopted for measuring the root biomass. The total biomass and the biomass of different tree organs within the stand were obtained by using both allometric method and the mean tree method. Besides, the leaf area of the stand was measured and the leaf area index was calculated so as to evaluate the productivity of the stand. In order to provide a theoretical basis for mangroves management and utilization, the yearly dynamic variation of the mean and annual net production and the variation tendency of the net assimilation rate with the increasing of the stand age have been analysed.
The paper deals with the biomass of average 20-aged Bruguiera gymnorrhiza stand. The vertical stratification method was adopted to measure the above ground biomass of different size-class trees in the stand. The tree mean growing area method was adopted for measuring the root biomass. The total biomass and the biomass of different tree organs within the stand were obtained by using both allometric method and the mean tree method. Besides, the leaf area of the stand was measured and the leaf area index was calculated so as to evaluate the productivity of the stand. In order to provide a theoretical basis for mangroves management and utilization, the yearly dynamic variation of the mean and annual net production and the variation tendency of the net assimilation rate with the increasing of the stand age have been analysed.
1991, 4(1): 30-37.
Abstract:
In this paper, technical and economic effect of main forestry measures such as loosening the soil, applying fertilizers, preserving the maternal culms and the integrated measures for the growth of Phyllostachys pubescens were analysed. The results showed: there are remarkable difference among different depths for loosening the soil. It is the best that loosening the soil 0~25 cm, and the reaction elasticity is the biggest and net receipts is the highest. Applying nitrogenous fertilizer or manure may obviously increase the output. It is the best to apply urea 20 kg per mu. The order to increase the output from large to small with manure are cake fertilizer, pig manure, rice straw, green grass. It is the best keeping 8-year-old culms in bamboo groves. In this case, the ANPV values are all bigger than zero, this indicates that loosening the soil 0~25 cm, applying urea 20kg per mu, keeping 8-year-old culms and the integrated measures are feasible. According to the different local cases in manpower, capacity and material resources, these measures can be adopted selectively. The benefit from applying urea 20 kg per mu is the best then in sequence loosening the soil 0~25 cm, integrated measures and preserving the 8-year-old maternal culms by the ANPVR level.
In this paper, technical and economic effect of main forestry measures such as loosening the soil, applying fertilizers, preserving the maternal culms and the integrated measures for the growth of Phyllostachys pubescens were analysed. The results showed: there are remarkable difference among different depths for loosening the soil. It is the best that loosening the soil 0~25 cm, and the reaction elasticity is the biggest and net receipts is the highest. Applying nitrogenous fertilizer or manure may obviously increase the output. It is the best to apply urea 20 kg per mu. The order to increase the output from large to small with manure are cake fertilizer, pig manure, rice straw, green grass. It is the best keeping 8-year-old culms in bamboo groves. In this case, the ANPV values are all bigger than zero, this indicates that loosening the soil 0~25 cm, applying urea 20kg per mu, keeping 8-year-old culms and the integrated measures are feasible. According to the different local cases in manpower, capacity and material resources, these measures can be adopted selectively. The benefit from applying urea 20 kg per mu is the best then in sequence loosening the soil 0~25 cm, integrated measures and preserving the 8-year-old maternal culms by the ANPVR level.
1991, 4(1): 38-43.
Abstract:
The investigation on the growth pattern and nutrient characteristics of Populus deltoides cv. "LUX" I-69 was initiated in 1982 in Han-shou County, Hunan Province. The results in the first three years (1982~1984) indicated that the local climate and soil was suitable for the growth of P. deltoides cv. "LUX" I-69. But there was significant difference in the growth of diameter breast-height (D.B.H.) among different years and different months. The growth of D.B.H. was slow in the first year with a peak in August. But the growth peak in the second year and third year was in June. The average growth in D.B.H. was 5.04cm annually. The contents of the major nutrient elements in the plants varied significantly with different months except Mg2+, but had no significant variation among different years. The variation pattern of nutrient contents within a year was similar to the D.B.H. growth pattern. The following are the annual average contents of some major nutrients: N:3.25%~3.31%, P2O5: 0.58%~0.59%, K2O:1.59%~1.61%, CaO: 3.17%~3.28%, MgO:0.54%~0.70%. This showed that the plants had a high nutrient level and a good condition including the soil nutrients supply, absorption and utilization existed in the tested plantations for the tree's growth.
The investigation on the growth pattern and nutrient characteristics of Populus deltoides cv. "LUX" I-69 was initiated in 1982 in Han-shou County, Hunan Province. The results in the first three years (1982~1984) indicated that the local climate and soil was suitable for the growth of P. deltoides cv. "LUX" I-69. But there was significant difference in the growth of diameter breast-height (D.B.H.) among different years and different months. The growth of D.B.H. was slow in the first year with a peak in August. But the growth peak in the second year and third year was in June. The average growth in D.B.H. was 5.04cm annually. The contents of the major nutrient elements in the plants varied significantly with different months except Mg2+, but had no significant variation among different years. The variation pattern of nutrient contents within a year was similar to the D.B.H. growth pattern. The following are the annual average contents of some major nutrients: N:3.25%~3.31%, P2O5: 0.58%~0.59%, K2O:1.59%~1.61%, CaO: 3.17%~3.28%, MgO:0.54%~0.70%. This showed that the plants had a high nutrient level and a good condition including the soil nutrients supply, absorption and utilization existed in the tested plantations for the tree's growth.
1991, 4(1): 44-49.
Abstract:
With the contrast of Pinus tabulaeformis, the introduction tests of P. sylvestriformis, P. densiflora, P. thunbergii and P. sylvestris var. mongo-lica, which included seven provenances, were conducted in three locations (elevation ranges 50-820 m) in Beijing mountain area. The results show that the growth of P. sylvestriformis is superior to that of P. tabulaeformis and the other pines have no advantage in comparison with P. tabulaeformis. There is significant variation among different provenances of P. sylvtstris var. mongolica in growth. The seed sources of Hulunberier, The Xiaoxinan Mountains and the southern part of The Daxinan Mountains are better than those of the northern part of The Daxinan Mountains.
With the contrast of Pinus tabulaeformis, the introduction tests of P. sylvestriformis, P. densiflora, P. thunbergii and P. sylvestris var. mongo-lica, which included seven provenances, were conducted in three locations (elevation ranges 50-820 m) in Beijing mountain area. The results show that the growth of P. sylvestriformis is superior to that of P. tabulaeformis and the other pines have no advantage in comparison with P. tabulaeformis. There is significant variation among different provenances of P. sylvtstris var. mongolica in growth. The seed sources of Hulunberier, The Xiaoxinan Mountains and the southern part of The Daxinan Mountains are better than those of the northern part of The Daxinan Mountains.
1991, 4(1): 50-56.
Abstract:
The Chinese Firorchard of Changle, Zhejiang Province was built in 1976, now there are elementary seed orchard in the areas of 514 mu and first-generation one of 136 mu. In this paper, the way guiding orchard construction, the main managing technology and the improving effect of the seed orchard are studied systematically. Through analysing materials, we find that in Zhejiang region where there is less of Chinese Fir resource, we may collect plus tree materials from original area to build Chinese Fir seed orchard, the latter generations of the parent tree in orchard gain obviously. The average volume of 7.5 years old progeny plantation increased over 30% compared with local check. The study also revealed that the climatic factor, especially the precepitaticn and the sunshine time in February and March, the source of parents, soil fertility, slope orientation etc are the important factors affecting the output and quality of seed in the orchard.
The Chinese Firorchard of Changle, Zhejiang Province was built in 1976, now there are elementary seed orchard in the areas of 514 mu and first-generation one of 136 mu. In this paper, the way guiding orchard construction, the main managing technology and the improving effect of the seed orchard are studied systematically. Through analysing materials, we find that in Zhejiang region where there is less of Chinese Fir resource, we may collect plus tree materials from original area to build Chinese Fir seed orchard, the latter generations of the parent tree in orchard gain obviously. The average volume of 7.5 years old progeny plantation increased over 30% compared with local check. The study also revealed that the climatic factor, especially the precepitaticn and the sunshine time in February and March, the source of parents, soil fertility, slope orientation etc are the important factors affecting the output and quality of seed in the orchard.
1991, 4(1): 57-64.
Abstract:
This paper reports the results of the study on the bionomics and application of Sycanus croceovittatus Dohrn in 1982~1984.It is an important predator of the larvae of some forest pests. In the insectary it has two generations each year in Guangzhou, Guangdong Province. The first generation occurs from early May to late October, the second generation from middle August to middle June of the following year. Winter is passed as 4~5 instar nymphs beneath stones and other objects in grassy plots. The eggs hatch 12.5~16.5 days after oviposition. The nymph has five instars, and its development lasts 48.0~223.5 days. The adults can live for 3.0~87.5 days. The preoviposition period is 16.5~38.0 days.The voracities of the nymphs and adults were tested with Dendrolimus punctatus Walker, Latoia lepida (Cramer), Scopelodes contracta Walker, Artona funeralis Butler and Selepa celtis Moore in different stages.Indoor and outdoor experiments indicated that it is effective for the control of some forest insect pests.
This paper reports the results of the study on the bionomics and application of Sycanus croceovittatus Dohrn in 1982~1984.It is an important predator of the larvae of some forest pests. In the insectary it has two generations each year in Guangzhou, Guangdong Province. The first generation occurs from early May to late October, the second generation from middle August to middle June of the following year. Winter is passed as 4~5 instar nymphs beneath stones and other objects in grassy plots. The eggs hatch 12.5~16.5 days after oviposition. The nymph has five instars, and its development lasts 48.0~223.5 days. The adults can live for 3.0~87.5 days. The preoviposition period is 16.5~38.0 days.The voracities of the nymphs and adults were tested with Dendrolimus punctatus Walker, Latoia lepida (Cramer), Scopelodes contracta Walker, Artona funeralis Butler and Selepa celtis Moore in different stages.Indoor and outdoor experiments indicated that it is effective for the control of some forest insect pests.
1991, 4(1): 65-68.
Abstract:
Aleiodes dendrolini (Matsumura) is an important braconid parasite of pine caterpillars (Dendrolimus spp.) in China. This paper reports the results of cold storage study in 1987~1989. The experimental materials were collected from Fengning, Xinglong Counties, Hebei Province, and Ningcheng County, Nei Mongol Autonomous Region from early March to 20th April. Some of the hosts parasitized by Aleiodes were placed in a refrigerator at 5±1℃: and the others in the laboratory under room temperature. The resultes are as follows: (1) There was no difference in the emergence rate and life-span of adult between Aleiodes dendrolimi which have been cold stored for 4~5 months and those of the checks (untreated). (2) The emergence periods of adults were influenced by the duration of cold storage. The longer the duration of cold storage, the earlier the beginning date of emergence and the shorter the duration of emergence. (3) Adults of Aleiodes would mate and oviposit normally after cold storage.(4) All of the hyperparasites were killed after cold storage for 4~5 months. When Aleiodes were immigrated from one location to other, cold storage method can be used for safety and effectiveness purposes.
Aleiodes dendrolini (Matsumura) is an important braconid parasite of pine caterpillars (Dendrolimus spp.) in China. This paper reports the results of cold storage study in 1987~1989. The experimental materials were collected from Fengning, Xinglong Counties, Hebei Province, and Ningcheng County, Nei Mongol Autonomous Region from early March to 20th April. Some of the hosts parasitized by Aleiodes were placed in a refrigerator at 5±1℃: and the others in the laboratory under room temperature. The resultes are as follows: (1) There was no difference in the emergence rate and life-span of adult between Aleiodes dendrolimi which have been cold stored for 4~5 months and those of the checks (untreated). (2) The emergence periods of adults were influenced by the duration of cold storage. The longer the duration of cold storage, the earlier the beginning date of emergence and the shorter the duration of emergence. (3) Adults of Aleiodes would mate and oviposit normally after cold storage.(4) All of the hyperparasites were killed after cold storage for 4~5 months. When Aleiodes were immigrated from one location to other, cold storage method can be used for safety and effectiveness purposes.
1991, 4(1): 69-71.
Abstract:
The response of photoperiodic diapause of Dendrolimus spp. varies with the larval development during its sensitive stages. The larvae have the strongest sensitivity to short photoperiods in the first instar and start to decrease in the second instar, and almost lost the sensitivity in the fourth instar. The larvae show higher sensitivity to shortday cycles in moulting stage. The longer the treatment received by larvae, the higher the ratio of diapause for the larvae in the third and fourth instars. The relationship between the photoperiodic reaction and the content of juvenile hormone is discussed.
The response of photoperiodic diapause of Dendrolimus spp. varies with the larval development during its sensitive stages. The larvae have the strongest sensitivity to short photoperiods in the first instar and start to decrease in the second instar, and almost lost the sensitivity in the fourth instar. The larvae show higher sensitivity to shortday cycles in moulting stage. The longer the treatment received by larvae, the higher the ratio of diapause for the larvae in the third and fourth instars. The relationship between the photoperiodic reaction and the content of juvenile hormone is discussed.
1991, 4(1): 72-73.
Abstract:
The locust looper, Ectropis excellens Butler, is an important insect pest in China. In 1988, a virus was isolated from a diseased larva of locust looper. Electronic micrographs revealed that it is of a new nuclear polyhedrosis virus. The size of polyhedral inclusion bodies of virus is about 0.64~1.92μm. They are triangular and round in shape. The virions measure about 292nm 71.3nm. They are rod-shaped.
The locust looper, Ectropis excellens Butler, is an important insect pest in China. In 1988, a virus was isolated from a diseased larva of locust looper. Electronic micrographs revealed that it is of a new nuclear polyhedrosis virus. The size of polyhedral inclusion bodies of virus is about 0.64~1.92μm. They are triangular and round in shape. The virions measure about 292nm 71.3nm. They are rod-shaped.
1991, 4(1): 74-78.
Abstract:
This paper presents a new method of measuring the height of trees through aerophotos. Based on the area unit centered at the root of a tree, a Digital Height Model (DHM) can be established by using "Moving Tilted Plane" to fit the terrain surface. With the DHM, the problem of invisibility of the root of a tree covered by shrubbery or bushes can be solved. As a result of an experiment, the measuring accuracy has been improved and the mean square deviation of 1.5 (m) for measuring the height of tree has been reached.
This paper presents a new method of measuring the height of trees through aerophotos. Based on the area unit centered at the root of a tree, a Digital Height Model (DHM) can be established by using "Moving Tilted Plane" to fit the terrain surface. With the DHM, the problem of invisibility of the root of a tree covered by shrubbery or bushes can be solved. As a result of an experiment, the measuring accuracy has been improved and the mean square deviation of 1.5 (m) for measuring the height of tree has been reached.
1991, 4(1): 79-85.
Abstract:
This paper deals with the biological community types from the eco-economic viewpoint in several lac plantations different at Zhenyuan county, Yunnan province from 1987 to 1989,studies have been conducted on the relationship between biological communities and their environments, between different community to their structures productions and values and on the correlations among different species as well as functions of intercropping crops in the communities. The results have shown that the economic output and its value of lac-grain-intercropping and tree-shrub-mixed forests are 2.4~4.4 and l.9~2.0 times higher than those of the checks respectively.
This paper deals with the biological community types from the eco-economic viewpoint in several lac plantations different at Zhenyuan county, Yunnan province from 1987 to 1989,studies have been conducted on the relationship between biological communities and their environments, between different community to their structures productions and values and on the correlations among different species as well as functions of intercropping crops in the communities. The results have shown that the economic output and its value of lac-grain-intercropping and tree-shrub-mixed forests are 2.4~4.4 and l.9~2.0 times higher than those of the checks respectively.
1991, 4(1): 86-90.
Abstract:
In this paper, 4 similarity coefficients and 9 cluster methods are used to analyse 26 types of Populus tomentosa Carr. and 5 relative species (include variety), besides, 26 characters are presented. According to the dendrogram, varieties of P. tomentosa were grouped into 9 groups. In addition, based on the comparison of 5 relative species, we consider P. davidiana Dode and P. alba L. var. pyramidalis Bge. may take part in the formation of some natural types of P. tomentosa.
In this paper, 4 similarity coefficients and 9 cluster methods are used to analyse 26 types of Populus tomentosa Carr. and 5 relative species (include variety), besides, 26 characters are presented. According to the dendrogram, varieties of P. tomentosa were grouped into 9 groups. In addition, based on the comparison of 5 relative species, we consider P. davidiana Dode and P. alba L. var. pyramidalis Bge. may take part in the formation of some natural types of P. tomentosa.
1991, 4(1): 91-95.
Abstract:
Studies on eluvial cinnamon soil under Pinus bungeana, Pinus tabulaeformis, Platycladus orientalis plantations are conducted in the Chinese Academy of Forestry.In this paper, the soil-forming conditions and the main soil properties, such as soil morphological characteristics, physical and chemical properties, were studied and discussed.
Studies on eluvial cinnamon soil under Pinus bungeana, Pinus tabulaeformis, Platycladus orientalis plantations are conducted in the Chinese Academy of Forestry.In this paper, the soil-forming conditions and the main soil properties, such as soil morphological characteristics, physical and chemical properties, were studied and discussed.
1991, 4(1): 96-100.
Abstract:
During the winters of 1987 and 1988, 29 sample sites of Pinus massoniana were selected in Susong County and Qianshan County of Anhui Province, and population densities of Dendrolimus punctatus were investigated according to a designed method. Through the analysis of the data, we obtained the following results:(1) The caterpillars thoroughly enter into the state of overwintering at the end of December.(2) In young trees, nearly all the caterpillars overwinter in the clumps of the needles; in higher trees, nearly ail the caterpillars go down to the crevices of the bark to overwinter, and most of them conceatrate on the lower-parts of the trunks under 2 m. The percent cf the number investigated from the lower-parts of the trunks under 2 m to the number from the whole tree (p) is related to the population density of the sample sites (g), the regression model is p=97.76-3.67√q.
During the winters of 1987 and 1988, 29 sample sites of Pinus massoniana were selected in Susong County and Qianshan County of Anhui Province, and population densities of Dendrolimus punctatus were investigated according to a designed method. Through the analysis of the data, we obtained the following results:(1) The caterpillars thoroughly enter into the state of overwintering at the end of December.(2) In young trees, nearly all the caterpillars overwinter in the clumps of the needles; in higher trees, nearly ail the caterpillars go down to the crevices of the bark to overwinter, and most of them conceatrate on the lower-parts of the trunks under 2 m. The percent cf the number investigated from the lower-parts of the trunks under 2 m to the number from the whole tree (p) is related to the population density of the sample sites (g), the regression model is p=97.76-3.67√q.
1991, 4(1): 101-105.
Abstract:
This paper intended to present the results of the series experiments conducted in Juxian County, Shandong Province, which aimed at determining the influence of water supply on wood property of Populus deltoides Bartr. cv. "Lux" I-69/55. In the spring of 1982, cuttings of the above-mentioned species were set with a spacing of 36 meters in the experimental field, which was later (during 1983 and 1986) divided into several small irrigation plots. Averaging about 0.45 hectare in size, each plot was supplied with a fixed quantity of water by means of dripping rainmaker systems; while the plots of the control only relied on natural rainfall. In contrast, the plots with lst-class water supply generally received artificially dripped water about 50 percent higher than the rainfall they received, and about 100 percent higher in regard to those with 2nd-class water supply of the same contrast. The results of the experiments, gained through three repetitions of the similar practice, indicated that irrigation could promote greatly the volume increment of this species without giving noticeable influences on such measurements of wood fiber as its length, width, cavum diameter, and double-wall thickness. However, it would lead a declining trend to most indexes of wood concerning its physical and mechanical properties, such as basic density, hardness, com-pressive strength, bending strength, shearing strength, and impact ductility.
This paper intended to present the results of the series experiments conducted in Juxian County, Shandong Province, which aimed at determining the influence of water supply on wood property of Populus deltoides Bartr. cv. "Lux" I-69/55. In the spring of 1982, cuttings of the above-mentioned species were set with a spacing of 36 meters in the experimental field, which was later (during 1983 and 1986) divided into several small irrigation plots. Averaging about 0.45 hectare in size, each plot was supplied with a fixed quantity of water by means of dripping rainmaker systems; while the plots of the control only relied on natural rainfall. In contrast, the plots with lst-class water supply generally received artificially dripped water about 50 percent higher than the rainfall they received, and about 100 percent higher in regard to those with 2nd-class water supply of the same contrast. The results of the experiments, gained through three repetitions of the similar practice, indicated that irrigation could promote greatly the volume increment of this species without giving noticeable influences on such measurements of wood fiber as its length, width, cavum diameter, and double-wall thickness. However, it would lead a declining trend to most indexes of wood concerning its physical and mechanical properties, such as basic density, hardness, com-pressive strength, bending strength, shearing strength, and impact ductility.
1991, 4(1): 106-110.
Abstract:
The results of the experiment indicated that there were significant differences in the growth, seed plot germination percent and so on between the families; Seedling growth of two families were remar-kbly greater than that of the check and that of three families were obviously less than the check in height of the seedlings; The growth of seedlings in each family was positively related to 1000-seeds weight of it; The cold resistance of the seedlings in winter displayed some difference between and within the families; The elite families shown in the experiment were as follows: 08-18 and 06-20.
The results of the experiment indicated that there were significant differences in the growth, seed plot germination percent and so on between the families; Seedling growth of two families were remar-kbly greater than that of the check and that of three families were obviously less than the check in height of the seedlings; The growth of seedlings in each family was positively related to 1000-seeds weight of it; The cold resistance of the seedlings in winter displayed some difference between and within the families; The elite families shown in the experiment were as follows: 08-18 and 06-20.
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